The Preparation And Electrochemical Property Of Coordination Polymers Based On Zinc Cap Modified Phosphomolybdate

POMs are mostly soluble anionic metal oxide clusters with oxygen-rich surfaces with unique physical and chemical properties.In the process of reversible multielectron redox transformations,POMs can maintain their unmatched structural under rather mild conditions,which have attracted particular interest in areas such as medicine,biology,magnetism,materials science and catalysis.At present,polyoxometalates modified chemical especially zinc cap modifiedis is still a hotspot in the field of POMs.So far,the report of the Mo-Zn cap Keggin Structure molybdate is still at its early stage.The aim of this thesis is to synthesize novel zinc cap modified heteropoly molybdate.To the best of our knowledge,POMOFs based on Zn-ε-Keggin units and bifunctional ligands have not been reported so far.Meanwhile,the Zn-ε-Keggin units as variable-valence metal clusters exhibited reversible redox activity,which can be directly utilized as anode materials for LIBs or as highly active electrocatalysts for hydrogen generation from water.In this article,we reported two tetrahedrally connected networks comprising ε-Keggin polymolybdate units capped by four Zn ions linked through the linear rigid bifunctional ligand,possessing an interpenetrated diamond topology successfully.Further,some properties of the hybrids have been studied by XRPD,elemental analysis,IR spectroscopy,thermogravimetric analysis.(TBA)3[PMoV8MoVI4O38(OH)2Zn4(IN)2](NENU-506)(TBA)3[PMoV8MoVI4O38(OH)2Zn4(PBA)2]·H2O(NENU-507).Two compounds exhibit exceptional chemical and hydrothermal stability.NENU-506 and NENU-507 show great tolerance to acid/base aqueous solutions at room temperature with a wide pH range from 2 to 12.Additionally,NENU-506 and NENU-507 is also stable after soaked in common organic solvents.Furthermore,NENU-507 was directly utilized as anode materials for LIBs,maintaining the three-dimensional(3D)rigid structure during lithiation/delithiation cycles,owing to its excellent chemical and thermal stability.The POM-based MOFs electrode materials showed an outstanding reversible specific capacity of 640 mA h g-1 at a current density of 100 mA g-1 over 100 cycles.Two novel POM-based inorganic-organic hybrid materials have been obtained by similar conditions by introducing N-/O-containing ligands to the systems.(TBA)5 [PMoV8MoVI4O38(OH)2Zn4(NTB)Cl](NENU-508)(TBA)[PMoV8MoVI4O38(OH)2Zn4(BDMPX)2]·5H2O(NENU-509)The compounds were characterized by IR,XRPD,and TGA.They exhibit not only good stability in air but also tolerance to acidic and basic media.Furthermore,they were employed as electrocatalysts for the hydrogen evolution reaction(HER)owing to the combination of the redox activity of a POM unit and the porosity of a MOF.